Shock absorbers



Aug. 10, 1965 A. HERMAN 3,199,637

SHOCK ABSORBERS Filed Dec. 3, 1963 46 y MM@ ATTORNEYS United StatesPatent O 3,199,637 SHSCK ABSRBERS Alejandro Herman, Perez Valenzuelai257, Apt. 11, Santiago, Chile Filed Dec. 3, 1963, Ser. No, 327,636 1Claim. (ill. 18S-96) The present invention refers to shock absorbersand, more particularly, to an improved construction for a double actionshock absorber which may 'be used for damping out lswaying in aresiliently suspended automotive vehicle. However, such use is merelycited as an example, since it is to be understood that the improvedshock absorber according to the invention is not limited to use inautomotive vehicles only.

The classical construction of a shock .absorber comprises a leak-proofcylinder iilled with a suitable liquid medium; inside lthe cylinderthere `is Ia perforated piston which is moved :by la piston-rod whichextend-s to the outside of said cylinder, so that said piston may bemoved axially -in the iluid medium. For this purpose, the piston isprovided ywith .a plurality of axially extending perforations, and theends of these perforations are closed by means of relatively resilientwashers.

Due .to the fact that such Ishock absorbers `are used on automotivevehicles, they are subject to very lfrequent and severe use; and theelastic washers, rw-hich have |the shape of a at ring, cannot readily bemade suiiiciently resistant to the lsevere strains involved. Theyconsequently do not long retain their flat shape or rthe resiliencerequired to sufficiently restrain the passage lof the liquidshock-absorbing medium to :adequately buffer the movement of the pistonand `its piston-rod. Hence lsu-:ll washers 'have a short useful life andthis implies that ordinary `shook absorbers must undergo frequent repairin lorder to change worm washers for new iones. Such construction alsomakes the regulating lof such yshock absorbers Ia lengthy Iand awkwardmatter, for it can 'only be carried out by making physical changes inthe washers, as by grinding, tiling, etc., and ,this tends towardsweakening the 4action of the shock absorber. Additionally,'over-correction cannot be checked, the correction being irreversible,except by using new and stronger wasn-ers.

The shook absorber of the invention, which is mainly characterized bythe shape of lits piston, provides ya means for obtaining a shock.absorber that has a 'long useful life, has excellent lshock-absorbingcharacteristics, and is easy to adjust, `as lwill be apparent from thefollowing detailed description when followed by an inspection of theattached drawing.

The new construction is simple, so that its cost ris low. Its variouscomponents are easy to manufacture, and

Vyet the characteristic of easy adjustment is maintained,

and this adjustment can be used to make the action either weaker `orstronger, as required.

#In the drawing, FIG. l is a schematic longitudinal section of a shookabsorber `according to the invention, and IFIGS. 2, 3 and 4, are crosssections taken respectively, along lines Il-IL 4lll-'III and lV-IV ofFlG. l.

Referring now to FIG. 1, the drawing depicts .a shock absorber composedof two concentric cylinders, an exter1or-cylinder ill), destined to actas a reservoir for excess liquid medium, and an inner cylinder :12,which is the shock .absorbing cylinder proper. Within the inner cylinderE2 there is slidably mounted `a piston .14, movable .toward either endof cylinder 12, in response to force applied through the piston rod 16to the piston 14 from outside the cylinders. The piston rod is lattachedto the piston by a nut y13 and two washers 20, ione above and the otherbelow the piston. The other or outer end of 3i9937 Patented Aug. 1G,i965 the piston rod is connected, for example, to the chassis of anautomotive vehicle, either by means of a bolt Sil acting on someresilient part connected to said chassis, or by means of a movable jointcomprising Ia washer, a hoo-k lor other means, in a `conventionalmanner. On 'the other hand, the outer or iixed cylinder :10 .isattached, at its base 4S, to a part of the suspension of the vehicle orother appropriate part, the movement of `which is to be damped. Thepiston l@ is perforated by a plurality of holes 22, usually disposed ina concentric circle around the piston rod. FIGURE 1 depicts six suchperforations, which extend axially of the cylinder. -Six perforationsare preferred, for a reason later to be given. These holes have meansfor controlling the passage of liquid therethrough; a certain number ofthese holes regulate passage of liquid from the lower to the upper sideof the piston, the other holes acting in the opposite direction. Thecontrol means comprises a valve seat 23, a small metall-ic ball,preferably of steel, 24, a coiled spring 26 which is used for graduatingthe pressure on said ball 24 and hence the pressure at which said valvewill allow liquid medium to pass through the hole controlled thereby,and finally, a hollow externally threaded bolt or plug 28, acting withina corresponding internal thread in the end of the hole that is farthestaway from the valve seat 23. The hollow bolt 28 has an am'al perforationand thus the liquid shock absorbing medium, when adequate pressureresults from the movement of the piston, will raise the ball 24 fromvalve seat 23 and the shock absorbing fluid will then low through theholes in the piston. These valve assemblies are alternately positionedin the successive holes in the piston, so that some of them open upwardwhile the others can open downward, and in the prefererd embodiment thisalternating of positions of the valve seats 22 obtains all the wayaround the ring of holes.

lhe pressure required to open each valve may be adjusted by simplyturning the threaded bolt 28 by means of a suitable tool, such as ascrew-driver or a polygonal rod.

once they have been adjusted, the setting of the bolts 28 is locked,preferably by means of the two Washers 20. In fact, if We use sixperforations in the piston, as in the preferred embodiment, three ofthese holes, alternating with the other three, will have theircorresponding bolts 2S on one side `o the piston, and the other threewill have them on the other side of the piston. Now, when tightening nut18 in order to lix the piston rod to the piston, both washers 20 will beclamped against the heads of the bolts 2S, securely locking said boltsagainst rotation. Thus the setting will not be lost. Naturally, theoutside diameter of washers 20 is so chosen that the washer does notcover the perforations in the threaded bolts 28, but just grips theinside edges of said bolts; thus a free ow of the hydraulic lluid isassured through said perforations. Of course, it would be possible touse washers of larger diameter, butin such case it would be necessary toperforate these Washers with axial holes corresponding to those in thethreaded bolts 28 and the washers must be so mounted, that these holesare in alignment. Likewise, the washers 20 should be so dimensioned,that at the point of contact with nut 1S and at the partwhere the end ofthe piston rod contacts the upper washer 2t?, there is a certain amountof play between the piston rod and the washers, such as -could beobtained by imparting a slight sphericity to their respective seats, andthus the washers may accommodate themselves to a situation in which thethree heads of the threaded bolts on one side of the piston whichcorrespond to each washer are not quite normal to the piston rod axis,when the bolts 28 have been adjusted to the desired positions In orderto maintain a desired position of the valves,

en and the place dened by these three heads is, as will happen in themajority of cases.

If for any reason it should be decided to use more or less than 6perforations in the piston, then special precautions should be taken byproviding suitable locking means for maintaining the adjustmentsimparted to the various threaded bolts as required by the valve settingsdetermined on. Such means might include lock-nuts, set screws, and soforth.

The other parts of the shock absorber are of a conventional type, butwill' be recited now in order that the operation of the improved shockabsorber may be better understood.

In the lower part of cylinder 12, as seen in FIG. l, there is a plug 32,which seals the lower end of the shock absorber in a leak-proof manner.The joint may be merely a pressure ht. This plug contains a valve,formed by a valve seat 34, a metal ball 36, and a small w-ire net or pin3S to retain the ball within the valve proper. If desired, a coil springmay be used to bias the ball against its seat. The ball can move a shortaxial distance within the valve bore. When piston 14 is raised (as seenin FIG. l), valve ball 36 lifts and admits hydraulic fluid fromreservoir to the inside of cylinder l2, below the piston 14. This willonly be the case when piston 14 has been raised in such a violentfashion, that there has not been material time for liquid medium to passfrom the upper part of piston 14 to its lower part through theperforations and valves in said piston, ie., through those valves thatcontrol passage downward of the hydraulic fluid.

In the upper part of the shock absorber, there is a cap i0 which is asliding t in the cylinder 10, and has a few suitable perforations 42,43, which interconnect the inner cylinder 12 with the outer cylinder 10.These small perforations allow alleviation of any excess pressure thatmay be produced in the hydraulic uid inside the cylinder 12 above thepiston 14, when said piston rises. Thus the liquid medium returns to thespace between the inner and outer cylinders. This cap 40 also has abushing 44 for guiding the piston rod and to take wear. Bushing 44 is asmall ybut wear-resisting part, and its renewal in case of eventual wearcan be carried out very simply and at a very low cost.

A threaded cover 4l is screwed into a cooperating screw thread on theinside of external cylinder 10 over cap 40, the object being to hold al1the parts together and in their proper places, as will be evident from astudy of FIGURE 1. For screwing this cover 41 on or off, its outer faceis provided with several small recesses 45, into which the points of anappropriate tool may be inserted. This cover has a suitable stuffing boxfor the passage of the piston rod, formed by a cavity 46 which receivesa suitable packing, for example, one of asbestos and graphite, and aconventional gland 49. This practically assures a leak-tight sealagainst loss of the hydraulic tluid in the shock absorber.

The double acting shock absorber of the invention can use as itshydraulic fluid any conventional lling fluid, mineral oils, or theso-called ash luids, as may be desired.

The shape of the piston shown in the drawings is merely schematic; thepiston may. obviously be provided with piston rings or with any other`type of packing of a conventional type (not shown), in order to enhanceits leak-proong qualities.

Among the` many advantages of the shock absorber of the invention, weshould mention the extreme simplicity t with which its effects may beadjusted. In fact, a mere turning of the lugs or bolts 28 in onedirection or the other, will change the biassing force on the valveballs 24 that control the passage of shock absorber tluid means throughpiston 14 and, in consequence the shock-absorbing eifect, which can thuskbe enhanced or lowered at will. Then again, it is possible so to setthe various valves by means of their bolts 28, that the effect of theshock absorber in one direction is greater, and less in the other, inthis case either greater up than down, or greater down than up. Shouldthe shock absorbing effect suddenly become considerably lessened, itwill surely mean that one or more of the springs 26 has failed and it isan easy matter to replace same. Fitting of the valve seats 22 can alsobe repaired without undue trouble.

Although the shock absorber according to the invention has beendescribed more specifically with reference to its use in an automotivevehicle, it must be evident that the scope of 'the invention is notlimited to this particular application, for a shocl; absorber can beused for many other purposes and may even, in some cases, be used in anlinclined or horizontal position. In the latter case it may be advisableto alter the form of the valve seat and its functioning at 36, 38, butthis does not require any substantial change in the invention, asdefined by the following claim.

What is claimed is:

In a double acting shock absorber comprising in combination an outercylinder which acts as a fluid reservoir, an inner cylinder within saidouter cylinder, a valve at one end of said inner cylinder which permitsfluid ow only from said outer cylinder `to the inner lcylinder of theshock absorber, orifices at the other end of said inner cylinder whichcommunicate with said outer cylinder, a piston within the innercylinder, and a piston rod attached to said piston which extends axiallyoutside the cylinders, the improvement according to which said pist-onis perforated by six axial holes, said shock absorber comprising checkvalves for said holes positioned to permit passage of said uid throughthree of said holes in one axial direction and through the other threeof said holes in the other axial direction, those check valvespermitting passage of fluid in said one direction being alternated withthose permitting passage in the other direction around a circle in thepiston concentric with said axis, said check valves being individuallyadjustable to provide various degrees of resistance to the passage loffluid through said holes and comprising setting means which protrude atall settings beyond a working surface of the piston, Washerk means onsaid piston rod lapping over said setting means While permitting thefree passage of uid through said holes, and means for applying pressureto said washer means to lock said setting means in position.

References Cited by the Examiner UNITED STATES PATENTS 1,745,357 2/30Crowell 267--8 X 2,467,098 4/49 Rossman 137-493 .8 3,084,566 4/ 63Pistillo 18S-88 FOREIGN PATENTS 920,709 11/54 Germany.

`ARTHUR L. LA POINT, Primary Exwmner.

'EUGENE G. BQTZ Examiner.

